NM_000274.4:c.199+303C>G

Variant names:

• chr10-124411670-G-C
• rs386833601
• NM_000274.4:c.199+303C>G

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP3 PP5_Moderate

The NM_000274.4(OAT):​c.199+303C>G variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: OAT NM_000274.4 intron
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:3
• Conservation: PhyloP100: -0.0530
• Publications: 0 publications found

Genes affected

OAT (HGNC:8091): (ornithine aminotransferase) This gene encodes the mitochondrial enzyme ornithine aminotransferase, which is a key enzyme in the pathway that converts arginine and ornithine into the major excitatory and inhibitory neurotransmitters glutamate and GABA. Mutations that result in a deficiency of this enzyme cause the autosomal recessive eye disease Gyrate Atrophy. Alternatively spliced transcript variants encoding different isoforms have been described. Related pseudogenes have been defined on the X chromosome. [provided by RefSeq, Jan 2010]

OAT Gene-Disease associations (from GenCC):

• ornithine aminotransferase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: ClinGen, Labcorp Genetics (formerly Invitae), G2P, Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 10-124411670-G-C is Pathogenic according to our data. Variant chr10-124411670-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 56119.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
OAT	NM_000274.4	c.199+303C>G		intron_variant	Intron 2 of 9	ENST00000368845.6	NP_000265.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
OAT	ENST00000368845.6	c.199+303C>G		intron_variant	Intron 2 of 9	1	NM_000274.4	ENSP00000357838.5

Frequencies

GnomAD3 genomes Cov.: 31

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, single submitter

Submissions by phenotype

Ornithine aminotransferase deficiency Pathogenic:2

Feb 01, 2018

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

-

Juha Muilu Group; Institute for Molecular Medicine Finland (FIMM)

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Hyperornithinemia Pathogenic:1

Apr 03, 2025

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: OAT c.199+303C>G is located at a position not widely known to affect splicing. Several computational tools predict a significant impact on normal splicing: Four predict the variant creates a 5' donor site. At least one publication reports experimental evidence that this variant affects mRNA splicing, causing inclusion of an intron sequencing and subsequent truncation of majority of the protein (Mitchell_1991). The variant was absent in 152118 control chromosomes. c.199+303C>G has been reported in the literature in a homozygous individual affected with Ornithine Aminotransferase Deficiency (Mitchell_1991). These data indicate that the variant is likely to be associated with disease. The following publications have been ascertained in the context of this evaluation (PMID: 1992472, 19823873). ClinVar contains an entry for this variant (Variation ID: 56119). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.96
CADD	Benign	21
DANN	Benign	0.74
PhyloP100		-0.053
Mutation Taster		=31/69	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
Splicevardb		3.0
SpliceAI score (max)		0.70		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.70		Position offset: 1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs386833601; hg19: chr10-126100239;